BAN240, Biogen’s Alzheimer’s drug candidate, produced positive data in a mid-stage study with a statistically significant 30% slowing in the rate of decline compared to the placebo arm in the high dose arm of the study at 18 months. But the data comes with a huge asterisk.

According to Endpoint News “critics quickly began pulling apart the data, finding enough holes in it to squelch Biogen’s share price , which plunged 12%. Eisai would quickly follow with its own drubbing after questions were raised in a call with Biogen execs about a decision by European regulators to move APOe4 carriers out of the high dose arm as they were worried by the threat of brain swelling — or ARIA-E — which they are prone to. APOe4 carriers are at higher risk of the disease as well as faster progression, and putting them in lower dose arms — while leaving APOe4 patients in the placebo group — raised the possibility that the researchers had made it possible for the high dose arm to hit statistical significance. Otherwise, it could have all been just another failure”.